Rotational metering pump for insulin patch

ABSTRACT

A rotary pump for a fluid metering system is provided. The rotary pump reciprocates, and is reversed by a signal from a limit switch that is deflected by an actuator arm on a rotating sleeve of the pump system. The rotary pump includes a plunger and optional stopper formed from a two-shot molding process, and including seals overmolded onto the head of the plunger and the head of the optional stopper.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.16/521,685, filed Jul. 25, 2019, which is a continuation-in-part of U.S.patent application Ser. No. 16/050,159, now U.S. Pat. No. 10,675,404,which is a continuation-in-part of U.S. patent application Ser. No.15/300,695, filed Sep. 29, 2016, now U.S. Pat. No. 10,132,308, which wasthe U.S. national stage of International Application No.PCT/US2015/024517, filed on Apr. 6, 2015, which claims priority to U.S.Provisional Application No. 61/976,361, filed Apr. 7, 2014. Each ofthese applications is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to metering systems for use inwearable medication infusion patches.

BACKGROUND OF THE INVENTION

Diabetes is a group of diseases marked by high levels of blood glucoseresulting from defects in insulin production, insulin action, or both.Diabetes can lead to serious health complications and premature death,but there are well-known products available for people with diabetes tohelp control the disease and lower the risk of complications.

Treatment options for people with diabetes include specialized diets,oral medications and/or insulin therapy. The primary goal for diabetestreatment is to control the patient's blood glucose (sugar) level inorder to increase the chances of a complication-free life. It is notalways easy, however, to achieve good diabetes management, whilebalancing other life demands and circumstances.

Currently, there are two principal modes of daily insulin therapy forthe treatment of type 1 diabetes. The first mode includes syringes andinsulin pens that require a needle stick at each injection, typicallythree to four times per day. These devices are simple to use andrelatively low in cost. Another widely adopted and effective method oftreatment for managing diabetes is the use of an insulin pump. Insulinpumps can help users keep their blood glucose levels within targetranges based on their individual needs, by providing continuous infusionof insulin at varying rates to more closely mimic the behavior of thepancreas. By using an insulin pump, users can match their insulintherapy to their lifestyles, rather than matching their lifestyles tohow an insulin injection is working for them.

However, conventional insulin pumps suffer from several drawbacks. Forexample, lead screw and piston type metering systems typically used ininsulin pumps are often cumbersome to users, requiring a large heightand a large a footprint.

Conventional insulin pumps also typically require a large number ofcomponents and moving parts, thereby increasing risks of mechanicalfailure.

Conventional insulin pumps also typically have too long a tolerance loopfor dose accuracy, depending on too many factors, which are sometimesdifficult to ascertain. This can result in a loss in dose accuracy.

Conventional insulin pumps also typically have too complex a fluid path.This can result in complicated or inadequate priming and air removal.

Conventional insulin pumps also typically require high precisionactuators, thereby increasing the cost of conventional patch pumps.

Some insulin pumps are also at risk of creating direct fluid pathsbetween a reservoir and a cannula of an insulin patch. This can resultin an overdose to a user.

Conventional insulin pumps also typically require complex sensingschemes. This can result in increased cost and reduced accuracy andreliability.

Conventional insulin pumps also typically have valves that are prone toleaking at elevated system back pressures. This can result in reducedaccuracy and reliability.

Conventional insulin pumps also typically require large working volumesand large system volumes exposed to potentially high back pressure. Thiscan result in reduced accuracy and reliability.

Conventional insulin patches also typically have low efficiency motorsrequiring large batteries, thereby increasing the size of the insulinpatch.

Accordingly, there is a need for a metering system with reduced heightand footprint, compared to conventional lead screw and piston typemetering systems, to increase comfort to users.

There is also a need for a metering system with a reduced number ofcomponents and moving parts, compared to conventional insulin pumps, toincrease the mechanical safety of insulin patches.

There is also a need for a metering system with a short tolerance loopfor dose accuracy, which depends on few factors, compared toconventional metering pumps, thereby increasing dose accuracy.

There is also a need for a metering system with a simple fluid path,compared to conventional metering systems, thereby simplifying primingand air removal.

There is also a need for a metering system utilizing a low precisionactuator, compared to conventional metering systems, thereby reducingthe cost of insulin patches.

There is also a need for a metering system with no direct fluid pathbetween the reservoir and the cannula, compared to conventional meteringsystems, thereby better safeguarding a user against overdose.

There is also a need for a metering system with simple sensing schemes,compared to conventional metering systems, thereby reducing cost andincreasing accuracy and reliability of insulin patches.

There is also a need for a metering system with valves that are robustwith respect to leaking at elevated system back pressures, compared toconventional metering systems, thereby increasing accuracy andreliability of insulin patches.

There is also a need for a metering system with a small working volumeand a low system volume exposed to potentially high back pressure,compared to conventional metering systems, thereby increasing accuracyand reliability of insulin patches.

There is also a need for a metering system requiring a high efficiencymotor with small batteries, compared to conventional metering systems,thereby reducing the size of insulin patches.

SUMMARY OF THE INVENTION

An aspect of illustrative embodiments of the present invention is tosubstantially address the above and other concerns, and provide a smalland reliable metering system.

An aspect of illustrative embodiments of the present invention is toprovide a metering system with reduced height and footprint, compared toconventional lead screw and piston type metering systems, to increasecomfort to users.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with a reduced number of components andmoving parts, compared to conventional insulin pumps, to increase themechanical safety of insulin patches.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with a short tolerance loop for doseaccuracy, which depends on few factors, compared to conventionalmetering pumps, thereby increasing dose accuracy. For example, inillustrative embodiments of the present invention, the tolerance loopfor dose accuracy is short, and depends upon only two readily measurabledimensions: a pump diameter and an axial dimension of a helical slot.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with a simple fluid path, compared toconventional metering systems, thereby simplifying priming and airremoval.

Another aspect of illustrative embodiments of the present invention isto provide a metering system utilizing a low precision actuator,compared to conventional metering systems, thereby reducing the cost ofinsulin patches. For example, in illustrative embodiments of the presentinvention, a mechanism can over-rotate at both ends of a stroke andstill maintain dose accuracy.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with no direct fluid path between thereservoir and the cannula, compared to conventional metering systems,thereby better safeguarding a user against overdose.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with simple sensing schemes, compared toconventional metering systems, thereby reducing cost and increasingaccuracy and reliability of insulin patches. For example, inillustrative embodiments of the present invention, sensing schemes arebased on contact switches.

Another aspect of illustrative embodiments of the present invention isto provide a metering system in which the mechanical stroke of a pumpallows for easy triggering of a cannula insertion mechanism.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with valves that are robust with respect toleaking at elevated system back pressures, compared to conventionalmetering systems, thereby increasing accuracy and reliability of insulinpatches. For example, in illustrative embodiments of the presentinvention, valves have no volume change when moving between states.

Another aspect of illustrative embodiments of the present invention isto provide a metering system with a small working volume and a lowsystem volume exposed to potentially high back pressure, compared toconventional metering systems, thereby increasing accuracy andreliability of insulin patches.

Another aspect of illustrative embodiments of the present invention isto provide a metering system using a high efficiency motor with smallbatteries, compared to conventional metering systems, thereby reducingthe size of insulin patches.

The foregoing and/or other aspects of the present invention are achievedby providing a metering system for use in a wearable insulin infusionpatch. For example, in illustrative embodiments of the presentinvention, the metering system is part of a larger fluidics sub-systemthat includes a flexible reservoir for storing insulin and a cannulaassembly for delivering the insulin into sub-cutaneous tissue. Themetering system draws a small dose of fluid from the reservoir and thenpushes it down the cannula line and into the patient. The fluid dose issmall relative to the reservoir volume, such that many pump strokes arerequired to completely empty the reservoir.

Additional and/or other aspects and advantages of the present inventionwill be set forth in the description that follows, or will be apparentfrom the description, or may be learned by practice of the invention.The present invention may comprise a method or apparatus or systemhaving one or more of the above aspects, and/or one or more of thefeatures and combinations thereof. The present invention may compriseone or more of the features and/or combinations of the above aspects asrecited, for example, in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects, advantages and novel features of illustrativeembodiments of the present invention will be more readily appreciatedfrom the following detailed description when read in conjunction withthe appended drawings, in which:

FIG. 1 shows a diagram of an architecture of an illustrative embodimentof a patch pump in accordance with the present invention;

FIG. 2 shows the layout of fluidic and metering system components of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIG. 3 shows a schematic exploded view of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIG. 4 shows the layout of a metering sub-system of an illustrativeembodiment of a patch pump in accordance with the present invention;

FIG. 5 shows a schematic cross-sectional view of a metering sub-systemof an illustrative embodiment of a patch pump in accordance with thepresent invention;

FIGS. 6A and 6B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, in a starting position;

FIGS. 7A and 7B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, during an intake stroke;

FIGS. 8A, 8B and 8C show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, during a valve state change after an intake stroke;

FIGS. 9A and 9B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, in an intake travel stop position;

FIGS. 10A and 10B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, during a discharge stroke;

FIGS. 11A, 11B and 11C show multiple views of a metering sub-system ofan illustrative embodiment of a patch pump in accordance with thepresent invention, during a valve state change after a discharge stroke;

FIGS. 12A and 12B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, after a pump cycle is complete;

FIG. 13 shows an exploded view of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIG. 14 shows a schematic exploded view of a pump assembly of anillustrative embodiment of a metering pump in accordance with thepresent invention;

FIG. 15 shows a schematic exploded view of a motor and gearbox assemblyof an illustrative embodiment of a metering pump in accordance with thepresent invention;

FIGS. 16A, 16B, 16C and 16D show multiple schematic views illustrating amethod of assembly of a piston into a sleeve in accordance with thepresent invention;

FIGS. 17A, 17B and 17C show multiple schematic views illustrating amethod of assembly of a plug into a sleeve in accordance with thepresent invention;

FIGS. 18A, 18B, 18C and 18D show multiple schematic views illustrating amethod of assembly of a sleeve into a manifold in accordance with thepresent invention;

FIG. 19 is a schematic cross-sectional view of a pump assembly of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIGS. 20A, 20B, 20C, 20D and 20E show multiple schematic cross-sectionalviews illustrating a method of valve state change in accordance with thepresent invention;

FIGS. 21A, 21B and 21C show multiple views of a limit switches for pumpand sleeve rotation in a metering sub-system of an illustrativeembodiment of a patch pump in accordance with the present invention;

FIGS. 22A, 22B and 22C show multiple schematic cross-sectional viewsillustrating a method of assembly of a pump into a gearbox in accordancewith the present invention;

FIGS. 23A, 23B and 23C show multiple views of a metering sub-system ofan illustrative embodiment of a patch pump in accordance with thepresent invention, in a starting position;

FIGS. 24A and 24B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, during a discharge stroke;

FIGS. 25A, 25B and 25C show multiple views of a metering sub-system ofan illustrative embodiment of a patch pump in accordance with thepresent invention, during a valve state change after a discharge stroke;

FIGS. 26A and 26B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, in a discharge rotational stop position;

FIGS. 27A and 27B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, during an intake stroke;

FIGS. 28A, 28B and 28C show multiple views of a metering sub-system ofan illustrative embodiment of a patch pump in accordance with thepresent invention, during a valve state change after an intake stroke;

FIGS. 29A and 29B show multiple views of a metering sub-system of anillustrative embodiment of a patch pump in accordance with the presentinvention, in an intake rotational stop position;

FIGS. 30A, 30B and 30C show multiple views of a metering sub-system ofan illustrative embodiment of a patch pump in accordance with thepresent invention, after a pump cycle is complete;

FIGS. 31A, 31B and 31C show multiple views of the motor and gearboxassembly as well as a modified pump assembly of an illustrativeembodiment of a metering assembly in accordance with the presentinvention;

FIG. 32 shows an exploded view of a pump assembly of an illustrativeembodiment of a metering assembly in accordance with the presentinvention;

FIGS. 33A and 33B show an assembly of a piston into a sleeve of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIGS. 34A, 34B, 34C, 34D and 34E show an assembly of a sleeve into amanifold of an illustrative embodiment of a patch pump in accordancewith the present invention;

FIG. 35 shows a cross section of a sleeve and manifold assembly of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIGS. 36A, 36B and 36C show multiple cross sections of a valve statechange of an illustrative embodiment of a patch pump in accordance withthe present invention taken as the sleeve rotates;

FIGS. 37A, 37B, 37C and 37D show a sleeve rotational limit switch of anillustrative embodiment of a patch pump in accordance with the presentinvention;

FIGS. 38A and 38B show an exploded view of a pump assembly withelastomeric port and piston seals over-molded onto a manifold and pumppiston respectively of an illustrative embodiment of a patch pump inaccordance with the present invention;

FIGS. 39A, 39B, 39C and 39D show an exploded view of a pump assemblywith an alternative rotational limit switch design of an illustrativeembodiment of a patch pump in accordance with the present invention;

FIG. 40 shows an exploded view of an illustrative embodiment of ametering assembly in accordance with the present invention;

FIG. 41 shows an assembled view of metering assembly of FIG. 40 ;

FIG. 42 shows a cross-section of metering assembly of FIG. 40 ;

FIGS. 43A, 43B and 43C show interaction of an interlock with a sleeve ofmetering assembly of FIG. 40 in accordance with an illustrativeembodiment of the present invention;

FIG. 44 shows a cross-section of another illustrative embodiment of ametering assembly in accordance with the present invention;

FIG. 45 is an isometric view of a limit switch and actuator arm usefulin an alternate exemplary embodiment of the present invention;

FIG. 46 is an isometric view of the limit switch and rotating sleeveaccording to the embodiment of FIG. 45 ;

FIG. 47 is a top view of the limit switch of FIG. 45 ;

FIG. 48 is a top view of the limit switch and actuator arm of FIG. 45 ;

FIG. 49 is an end view of the rotating sleeve of FIG. 46 ;

FIG. 50 is a cross sectional elevation view of the limit switch andactuator arm of FIG. 45 ;

FIGS. 51A and 51B are charts illustrating relative displacement of thelimit switch and rotating sleeve according to an exemplary embodiment ofthe invention;

FIGS. 52 through 58 illustrate different perspective views of animproved plunger for a pump according to another exemplary embodiment ofthe invention;

FIGS. 59 through 62 illustrate different perspective views of anovermolded seal for the improved plunger of FIGS. 52 through 58 ;

FIGS. 62 through 67 illustrate different perspective views of animproved pump plug;

FIG. 68 is an exploded view of the pump system utilizing the improvedplunger, plug and overmolded seals of an exemplary embodiment of theinvention; and

FIG. 69 is a flow chart of a method of manufacturing a pump according toan exemplary embodiment of the invention.

Throughout the drawings, like reference numbers should be understood torefer to like elements, features and structures.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

As will be appreciated by one skilled in the art, there are numerousways of carrying out the examples, improvements, and arrangements of ametering system in accordance with embodiments of the present inventiondisclosed herein. Although reference will be made to the illustrativeembodiments depicted in the drawings and the following descriptions, theembodiments disclosed herein are not meant to be exhaustive of thevarious alternative designs and embodiments that are encompassed by thedisclosed invention, and those skilled in the art will readilyappreciate that various modifications may be made, and variouscombinations can be made, without departing from the invention.

Although various persons, including, but not limited to, a patient or ahealthcare professional, can operate or use illustrative embodiments ofthe present invention, for brevity an operator or user will be referredto as a “user” hereinafter.

Although various fluids can be employed in illustrative embodiments ofthe present invention, for brevity the liquid in an injection devicewill be referred to as “fluid” hereinafter.

Illustrative embodiments in accordance with the present invention aredepicted in FIGS. 1-30 . In an illustrative embodiment according to thepresent invention, a metering system is provided for use in a wearableinsulin infusion patch. For example, in illustrative embodiments of thepresent invention, the metering system is part of a larger fluidicssub-system that includes a flexible reservoir for storing insulin and acannula assembly for delivering the insulin into sub-cutaneous tissue.The metering system draws a small dose of fluid from the reservoir andthen pushes it down the cannula line and into the patient. The fluiddose is small relative to the reservoir volume, such that many pumpstrokes are required to completely empty the reservoir.

FIG. 1 shows a diagram of an architecture of a patch pump 100 inaccordance with an exemplary embodiment of the present invention. Thepatch pump 100 includes a fluidics sub-system 120, an electronicssub-system 140 and a power storage sub-system 160.

The fluidics sub-system 120 includes a fill port 122 in fluidcommunication with a reservoir 124. The reservoir 124 is adapted toreceive fluid from a syringe, through the fill port.

The fluidics sub-system 120 further includes a volume sensor 126mechanically coupled to the reservoir 124. The volume sensor 126 isadapted to detect or determine the fluidic volume of the reservoir.

The fluidics sub-system 120 further includes a metering subsystem 130,which includes an integrated pump and valve system 132 mechanicallycoupled to a pump and valve actuator 134. The integrated pump and valvesystem 132 is in fluid communication with the reservoir 124 of thefluidics sub-system 120, and is actuated by the pump and valve actuator134.

The fluidics sub-system 120 further includes a cannula mechanism havinga deployment actuator 128 mechanically coupled to a cannula 129. Thedeployment actuator 128 is adapted to insert the cannula 129 into auser. The cannula 129 is in fluid communication with the integrated pumpand valve system 132 of the metering sub-system 130.

The fluidics sub-system 120 further includes an occlusion sensor 136mechanically coupled to a fluid pathway between the cannula 129 and theintegrated pump and valve system 132. The occlusion sensor 136 isadapted to detect or determine an occlusion in the pathway between thecannula 129 and the integrated pump and valve system 132.

The electronics sub-system 140 includes volume sensing electronics 142electrically coupled to the volume sensor 126 of the fluidics sub-system120, a pump and valve controller 144 electrically coupled to the pumpand valve actuator 134 of the metering sub-system 130, occlusion sensingelectronics 146 electrically coupled to the occlusion sensor 136 of thefluidics sub-system 120, and optional deployment electronics 148electrically coupled to the cannula 129 of the fluidics subsystem. Theelectronics sub-system 140 further includes a microcontroller 149electrically coupled to the volume sensing electronics 142, the pump andvalve controller 144, the occlusion sensing electronics 146, and thedeployment electronics 148.

The power storage sub-system 160 includes batteries 162 or any otherelectrical power source known in the art. The batteries 162 can beadapted to power any element or electronic component of the patch pump100.

FIG. 2 shows the layout of fluidic and metering system components of apatch pump 200 in accordance with an exemplary embodiment of the presentinvention. The patch pump 200 includes a metering sub-system 230,control electronics 240, batteries 260, a reservoir 222, a fill port 224and a cannula mechanism 226. The elements of patch pump 200 aresubstantially similar to and interact substantially similarly to theelements of illustrative patch pump 100 that are referred to by similarreference numbers.

FIG. 3 is an exploded view of a metering sub-system 300 of a patch pumpin accordance with an exemplary embodiment of the present invention. Themetering sub-system 300 includes a DC gear motor 302 mechanicallycoupled to a pump piston 304 disposed within a pump casing 306. The pumppiston 304 is mechanically coupled to a pump housing 308 by a couplingpin 310. The metering sub-system 300 further includes a pump seal 312between the pump piston 304 and the pump housing 308. The meteringsub-system 300 further includes port seals 314 on a seal carriage 316disposed within a valve housing 318.

In an exemplary embodiment of the present invention, the output shaft320 of the DC gear motor can rotate 360° in either direction. The pumppiston 304 can rotate 360° in either direction and can translate byabout 0.050 inches. The pump housing 308 can rotate 180° in eitherdirection. The pump casing 306, the port seals 314, the seal carriage316 and the valve housing 318 are preferably stationary.

The metering sub-system 300 includes a positive displacement pump withintegrated flow control valve & mechanical actuator and drive system.The pump includes a piston 304 and rotationally actuated selector valve.The metering system pulls a precise volume of insulin from a flexiblereservoir into a pump volume 320 formed between the piston 304 and thepump housing 308 (see FIG. 5 ), and then expels this insulin volumethrough a cannula into a patient's subcutaneous tissue, administeringinsulin in small, discrete doses. The pump stroke creates positive andnegative pressure gradients within the fluid path to induce flow. Thestroke and internal diameter of the pump volume determine the nominalsize and accuracy of the dose. The fluid control valve is activelyshuttled between the reservoir and cannula fluid ports at each end ofthe pump stroke to alternately block and open the ports to ensure thatfluid flow is unidirectional (from the reservoir to the patient) andthat there is no possibility of free flow between the reservoir and thepatient.

FIG. 4 is an assembly view of the metering sub-system 300 according toan exemplary embodiment of the present invention. Also illustrated are amotor to piston coupling 322, a piston to pump housing coupling 324, areservoir port 326 and a cannula port 328.

FIG. 5 is a cross-sectional view of the metering sub-system 300 of anexemplary embodiment of the present invention. As illustrated, a pumpvolume 320 is formed between the piston and the pump housing 308. Thepump housing includes a side port 330 that alternates in orientationbetween the reservoir port 326 and the cannula port 328 as the motor 302reciprocates the pump, as will be described in greater detail below.

In operation, an illustrative cycle of a metering system according tothe present invention includes 4 steps: a 180° pump intake(counterclockwise) (when viewing from the pump toward the motor); a 180°valve state change (counterclockwise); a 180° pump discharge(clockwise); and a 180° valve state change (clockwise). A complete cyclerequires a full rotation (360°) in each direction.

FIG. 6A is an isometric view, and FIG. 6B is a cross-section view of themetering sub-system 300 in a starting position. In the startingposition, the pump piston 302 is fully extended, the pump housing blocksthe cannula port flow path at the cannula port 328, and the reservoirport 326 is open to the side port 330 of the pump housing 308, and arotational limit sensor 332 is engaged. Pump housing 308 includes ahelical groove 334 which receives coupling pin 310. Piston 304 is insliding engagement with pump housing 308 such that as piston 304 rotateswithin pump housing 308 (by rotational force of the motor 302), couplingpin 310 slides along helical groove 334 to force piston 304 to translateaxially with reference to pump housing 308. In this embodiment, thehelical groove 334 is formed into pump housing 308 and provides for 180°of rotation for coupling pin 310.

FIG. 7A is an isometric view, and FIG. 7B is a cross-section view of themetering sub-system 300 during an intake stroke. The DC motor 302 turnsthe pump piston 304, which is driven along the helical groove 334(rotating and translating) of the pump housing 308 via the coupling pin310. The pump piston 304 translates toward the DC motor 302, drawingfluid into the increasing pump volume 320. During the intake stroke,friction between the seals and the outside diameter of the pump housing308 is preferably be high enough to ensure that the pump housing 308does not rotate. The pump housing 308 is stationary, while the pumpvolume 320 is expanding. The cannula port 328 is blocked, while thereservoir port 326 is open to fluid flowing into the expanding pumpvolume 320. There is a sliding engagement between the motor 302 and thepump piston 304.

FIG. 8A is an assembly view, FIG. 8B is a detail view, and FIG. 8C is across-section view of the patch pump during a valve state change afteran intake stroke. Torque is transmitted from the drive shaft of themotor 302, to the pump piston 304, and then to the pump housing 308 viathe coupling pin 310. Once the coupling pin 310 rotates to the end ofthe helical groove 334, further rotation of motor 302 causes thecoupling pin 310 to rotate pump housing 308 and pump piston 304 togetheras a unit without relative axial translation. The side port 330 on thepump housing 308 rotates between the reservoir port 326 and the cannulaport 328. Surface tension of the pump housing 308 side port 330 holdsthe fluid in the pump volume 320. The pump housing side port 330 movesout of alignment with the reservoir port 326 and into alignment with thecannula port 328 over the next 180° rotation of the motor 302. Inbetween, both the cannula port 328 and the reservoir port 326 areblocked. The coupling pin 310 is at the end of the helical groove 334and transmits torque to the pump housing 308. The coupling pin 310 locksthe pump piston 304 and the pump housing 308 together to preventrelative axial motion between the two components. The pump piston 304and the pump housing 308 therefore rotate as a unit and do not translaterelative to each other. The pump housing 308 rotates while the pumpvolume 320 is fixed and the pump piston 304 rotates. The seals 314, theseal carriage and the valve housing 318 are preferably stationary.

FIG. 9A is an assembly view, and FIG. 9B is a cross-section view of themetering sub-system in an intake travel stop position, ready to infuse.As illustrated, the side port 330 of the pump housing 308 is alignedwith the cannula port 328, the pump volume 320 is expanded, and thereservoir port 326 is blocked. The rotational limit sensor 332 isengaged by a feature on the rotating pump housing 308. The motor 302,the pump piston 304, and the pump housing 308 are stationary.

FIG. 10A is an assembly view, and FIG. 10B is a cross-section view ofthe metering sub-system 300 during a discharge stroke. At the end of theintake stroke the pump housing 308 engages the limit switch 332, whichcauses the DC motor 302 to switch directions. Accordingly, the motor 302turns the piston 304 and drives the coupling pin 310 down the helicalgroove 334 of the pump housing 308, causing the piston 304 to translateaxially. The pump piston 304 translates axially away from the DC motor302, pushing fluid from the pump volume 320 and out of the cannula port328 to the cannula. During the discharge stroke, friction between theseals 314 and the outside diameter of the pump housing 308 is preferablyhigh enough to ensure that the pump housing 308 does not rotate. Thecannula port 328 is open to fluid flowing out of the collapsing pumpvolume 320. The reservoir port 326 is blocked. The pump housing 308 isstationary while the pump volume 320 is collapsing and the pump piston304 rotates and translates in a helical motion. The motor is slidinglyconnected to the piston 304 to accommodate the translation motion of thepiston as it rotates in the helical groove 334.

FIG. 11A is an assembly view, FIG. 11B is a detail view, and FIG. 11C isa cross-section view of the metering sub-system 300 during a valve statechange after a discharge stroke. Torque is transmitted from the driveshaft of the motor 302, to the pump piston 304, and then to the pumphousing 308 via the coupling pin 310. The pump housing 308 and pumppiston 304 rotate as a unit with no relative axial motion. The side port330 on the pump housing 308 rotates between the reservoir port 326 andthe cannula port 328, both of which are blocked during the rotation.Surface tension of the pump housing 308 side port 330 holds the fluid inthe pump volume 320. The coupling pin 310 locks the pump piston 304 andthe pump housing 308 together to prevent relative axial motion betweenthe two components. Therefore, the pump piston 304 and the pump housing308 rotate as a unit and do not translate relative to each other. Thepump housing 308 rotates while the pump volume 320 is fixed. The seals314, the seal carriage and the valve housing 318 are preferablystationary.

FIG. 12A is an assembly view, and FIG. 12B is a cross-section view ofthe metering sub-system 300 after a pump cycle is complete. The pumpmechanism (piston 304) is fully extended, completing the pump cycle. Therotational limit sensor 332 is engaged to reverse the motor 302 andbegin the pump cycle again. The cannula port 328 is blocked, while thereservoir port 326 is open to the flow path from the reservoir.

In the foregoing exemplary embodiment, the pump piston both rotates andtranslates, the pump housing rotates, and the valve housing isstationary. However, it should be appreciated that in other embodiments,the system may be configured so that the pump piston rotates, the pumphousing both rotates and translates, and the valve housing translates,or any other combination of motions causing the pump volume to increaseand decrease, and a port in communication with the pump volume to movefrom alignment with the reservoir port to alignment with the cannulaport.

In the foregoing exemplary embodiment, the pump stroke and valve statechange are configured with 180° rotational actuation from the motor.However, it should be appreciated that any suitable angle may beselected for the segments of the pump cycle.

In the foregoing exemplary embodiment, there is an atmospheric breakbetween the cannula and reservoir ports during the valve state change.However, it should be appreciated that in other embodiments, the sealsmay be configured, or additional seals may be added, to eliminate theatmospheric break and seal the pump and valve system during the statechange.

In the foregoing exemplary embodiment, a DC gear motor is used to drivethe pump and valve. However, in other embodiments, any suitable drivemechanism may be provided to drive the pump and valve. For example,solenoids, nitinol wire, voice coil actuators, piezo motors, wax motors,and/or any other type of motor known in the art can be used to drive thepump.

In the foregoing exemplary embodiment, the pump uses full dischargestrokes. However, it should be appreciated that in other embodiments, asystem with sequential incremental discharge strokes may be used todispense finer doses.

In the foregoing exemplary embodiment, the pump uses on/off limitswitches to determine the state of the system at the limits ofrotational travel. However, it should be appreciated that in otherembodiments, other sensors with the capability to determine intermediatestates, such as an encoder wheel and optical sensor, may be used toimprove the resolution of the sensing scheme.

It should be appreciated that the internal diameter of the pump may beadjusted to change the nominal output per cycle.

In the foregoing exemplary embodiment, the pump uses elastomeric O-ringseals. However, it should be appreciated that other arrangements mayalso be used. For example, fluid seals may be molded directly onto theseal carriage, other elastomeric seals such as quad rings could be used,or other seal materials such as Teflon or polyethylene lip seals areused.

In alternate embodiments of the invention, the motion of the pump can beused to initiate or trigger the deployment of the cannula.

In the foregoing exemplary, the system advantageously uses abi-directional actuation. The motor rotation is reversed to alternatebetween intake and discharge strokes. This provides a safety featurethat prevents runaway in the event of a malfunctioning motor. The motormust reciprocate in order for the pump to continue delivering medicationfrom the reservoir. However, it should be appreciated that in otherembodiments, the metering system is designed to use a unidirectionalactuator.

In the foregoing exemplary embodiment, the system uses a pouch reservoirwith two flexible walls. However, in other embodiments, the reservoircan be formed in any suitable manner, including with one rigid and oneflexible wall.

FIG. 13 is an exploded view of a metering sub-system 1300 for a patchpump in accordance another illustrative embodiment of the presentinvention. The metering sub-system 1300 includes a motor and gearboxassembly 1302 and a pump assembly 1304.

FIG. 14 is an exploded view of the pump assembly 1304. The pump assembly1304 includes a piston 1306 mechanically coupled to a sleeve 1308through a coupling pin 1310, within a pump manifold 1312. The pumpassembly 1304 further includes port seals 1314, a plug 1316, a sleeverotational limit switch 1318 and an output gear rotational limit switch1320.

The piston 1306 rotates a total of 196° in either direction and cantranslate by about 0.038 inches. The sleeve 1308 and the plug 1316rotate together (as a pair) 56° in either direction. The pump manifold1312 and the port seals 1314 are stationary.

FIG. 15 is an exploded view of the motor and gearbox assembly 1302. Themotor and gearbox assembly 1302 includes a gearbox cover 1322, compoundgears 1324, an output gear 1326, axles 1328, a gearbox base 1330, amotor pinion gear 1332 and a DC motor 1334.

FIGS. 16A-16D illustrate the assembly and operation of the piston 1306,sleeve 1308 and coupling pin 1310. FIG. 16A illustrates the piston 1306,which includes a press fit hole 1338 which receives the coupling pin1310, as well as a piston seal 1340, which tightly seals the pistonwithin the sleeve 1308. Sleeve 1308 includes a helical groove 1342.Piston 1306 is pressed axially into sleeve 1308, and then coupling pin1310 is press fit into hole 1338 through the helical groove 1342. Thisprovides operation similar to the above described embodiment, whererotation of the piston 1306 causes axial translation of the piston 1306relative to the sleeve 1308 due to interaction of the coupling pin 1310and the helical groove 1342. FIG. 16B illustrates the piston 1306,sleeve 1308 and coupling pin 1310 assembled, with coupling pin 1310shown at the lower end of helical groove 1342. FIG. 16C illustrates theaxial stroke length 1344 of the piston 1306 relative to the sleeve 1308as a result of the helical groove 1342. FIG. 16D illustrates taperedfaces 1346 that are preferably provided at the ends of the helicalgroove 1342 to center the coupling pin 1310 within the groove 1342.

FIG. 17A illustrates assembly of the plug 1316 with sleeve 1308. Asshown, plug 1316 includes a key 1346, and a seal 1348. Seal 1348provides a tight fit for the plug within sleeve 1308. Sleeve 1308 isprovided with a recess 1350 adapted to receive key 1346. The key 1346locks plug 1316 in rotational engagement with sleeve 1308. The plug 1316is pressed against the end face of the (advanced) piston 1306 duringassembly in order to minimize air in the pump chamber. Friction betweenseal 1348 and the inner surface of sleeve 1308 retain the plug 1316axially. With appropriate selection of seal diameters, squeeze, andmaterials, the plug 1316 can also serve as an occlusion or overpressuresensor. Pump pressures greater than the threshold value will cause theplug 1616 to move axially and disengage with the sleeve rotational limitswitch 1318. Friction holds the plug 1316 in position against pressuresbelow a desired threshold. FIGS. 17B and 17C illustrate axial movementof the piston 1306 within sleeve 1308. FIG. 17B illustrates the piston1306 in a first state with minimal or no pump volume between piston 1306and plug 1316. As shown, coupling pin 1310 is abutted against the lowestend of helical groove 1342. FIG. 17C illustrates the piston 1306 in asecond state with maximum pump volume 1352 between piston 1306 and plug1316. As shown, coupling pin 1310 is abutted against the highest end ofhelical groove 1342.

FIGS. 18A-18D illustrate the assembly of the sleeve 1308 into manifold1312. As illustrated in FIG. 18A, manifold 1312 includes port seals 1314to seal a reservoir port 1354 and a cannula port 1356, respectively. Asmall side hole 1358 (See FIG. 17B) on the sleeve rotationally shuttlesback and forth between the two ports, which are 56 degrees apart. Asshown in FIG. 18B, sleeve 1308 includes a tab 1360, and manifold 1312includes a corresponding slot 1362 to permit sleeve 1308 to be assembledinto the manifold 1312. FIG. 18C illustrates a manifold window 1364provided in the manifold. Tab 1360 is received within and travels inwindow 1364 when the sleeve 1308 is assembled into manifold 1312. Tab1360 and window 1364 interact to permit sleeve 1308 to rotate betweentwo positions while preventing axial translation of the sleeve 1308relative to the manifold 1312. Sleeve 1308 rotates between a firstposition in which side hole 1358 is aligned with the reservoir port 1354and a second position in which the side hole 1358 is aligned with thecannula port 1356. FIG. 18D illustrates the sleeve 1308 assembled intothe manifold 1312, with tab 1360 located within manifold window 1364.

FIG. 19 is a cross section of the assembled metering system. Asillustrated, port seals 1314 are face seals which are compressed betweenthe sleeve 1308 OD and recessed pockets in the manifold 1312. As alsoillustrated, tab 1360 is located within manifold window 1364, and sidehole 1358 is shown in transition between the reservoir port 1354 and thecannula port 1356. Output gear 1326 includes a cam feature 1366 thatengages rotational limit switch 1320 to signal the end of rotationalmovement of the piston 1306 and sleeve 1308 in either direction.

FIGS. 20A-20E are cross-section views illustrating rotation of thesleeve 1308 within manifold 1312 to move the side hole from alignmentwith reservoir port 1354 to alignment with cannula port 1356. FIG. 20Aillustrates side hole 1358 aligned with the reservoir port 1354. Whilein this position, piston 1306 moves away from plug 1316 to fill volume1352 with fluid from the reservoir. FIG. 20B illustrates the sleeve 1308as it begins to rotate towards the cannula port 1356. In this position,the side hole 1358 is sealed by the seal 1314 on the reservoir port1354. For this reason, the seal 1314 and the side hole 1358 diameter arepreferably selected such that seal 1314 covers the opening of the sidehole 1358. FIG. 20C illustrates the side hole 1358 of sleeve 1308between the seal 1314 of the reservoir port 1354 and the seal 1314 ofthe cannula port 1356. In this position, neither seal 1314 blocks theside hole 1358, but surface tension of the liquid holds the liquid inthe pump chamber. FIG. 20D illustrates the side hole 1358 rotatedfurther to a position where the seal 1314 of the cannula port 1356covers the opening of the side hole 1358. Finally, FIG. 20E illustratesthe side hole 1358 rotated into alignment with the cannula port 1356.While in this position, the piston 1306 translates axially to reduce thevolume 1352, forcing the fluid out of the cannula port 1356 and to thecannula.

FIGS. 21A-21C illustrate operation of the limit switches. As shown inFIG. 21A, plug 1316 includes a cam feature 1368 that interacts withlimit switch 1318. As the sleeve 1308 and plug 1316 rotate, the camfeature 1368 causes metal flexures of limit switch 1318 to come intocontact with one another, until the plug 1316 has fully rotated to thenext position. A bump 1370 in one of the flexures rests in the camfeature 1368 as illustrated in FIG. 21C when the plug 1316 is in eitherend point of the plug rotation. The limit switch 1318 opening andclosing each rotation cycle signals that the plug 1316 remains in properalignment with the limit switch 1318. Under overpressure or occlusionconditions, increased pressure will cause plug 1316 to slide out fromsleeve 1308, and out of alignment with the limit switch 1318. Thus,overpressure conditions are detected. Limit switch 1320 is engaged bycam feature 1366 of output gear 1326 at each end of the rotation cycle.This signals the motor 1334 to reverse directions. With two metalflexures, as illustrated, it is not possible to determine from the limitswitch which rotation cycle was completed. However, as will beappreciated, a third flexure would permit the direction of engagement tobe determined.

FIGS. 22A-22C illustrate the assembly of the motor and gearbox 1302 withthe pump assembly 1304. As illustrated in FIGS. 22A and 22B, motor andgearbox 1302 includes an opening 1372 to receive rotational limit switch1320. In this manner, output gear 1326, which is internal to the gearboxhousing, can access and engage the flexures of limit switch 1320. Motorand gearbox 1302 also includes an axial retention snap 1374 so that thepump assembly 1304 may be snap-fit to the motor and gearbox 1302. Motorand gearbox 1302 includes a rotational key 1376 within a pump-receivingsocket 1378 to receive pump assembly 1304 and to prevent rotation of thepump assembly 1304 relative to the motor and gearbox 1302. Output gear1326 includes a slot 1380 (FIG. 22B) adapted to receive a tab 1382 (FIG.22C) provided on the piston 1306. When assembled, tab 1382 is receivedinto slot 1380 so that the output gear 1326 can transmit torque to thepiston 1306. As the output gear 1326 rotates, the pump piston tab 1382both rotates and slides axially in the slot. Metal spring flexures onthe motor connections and limit switches are used to make electricalcontact with pads on a circuit board during final assembly.

In operation, the pump cycle of the above described embodiment includesfive steps. First, an approximately 120° pump discharge(counterclockwise when viewing from the pump toward the gearbox); a 56°valve state change (counterclockwise); a 140° pump intake (clockwise); a56° valve state change (clockwise); and an approximate 20° jog(counterclockwise) to clear the limit switch. A total pump cyclerequires 196 degrees of output gear rotation in each direction.

FIGS. 23A-30C illustrate a pump cycle. For the sake of clarity, only theoutput gear 1326 of the gearbox assembly 1302 is shown in the figures.

FIG. 23A illustrates a starting position. As shown, the cam 1366 ofoutput gear 1326 is not in contact with rotational limit switch 1320,such that the flexures are not in contact with one another. The pumppiston 1306 is retracted, as shown by the position of the coupling pin1310 within helical groove 1342 in FIG. 22C. In this position, sleeve1308 blocks the reservoir flow path, the cannula port 1356 is open tothe side hole 1358 of the sleeve 1308, and the rotational limit sensor1320 and the sleeve sensor 1318 (See FIG. 23B) are both open.

FIGS. 24A and 24B illustrate the metering sub-system during a dischargestroke. The output gear 1326 turns the pump piston 1306 in a firstrotational direction (see arrow in FIG. 24B), which is driven along thehelical path of the helical groove 1342 in the sleeve 1308 via thecoupling pin 1310 (See FIG. 24A). The pump piston 1306 translates awayfrom the gearbox while rotating, expelling fluid from the pump chamber1352 and out of the cannula port 1356. During the discharge stroke,friction between the port seals 1314 and the outside diameter of thesleeve 1308 should be high enough to ensure that the sleeve 1308 doesnot rotate during this portion of the cycle.

FIGS. 25A-25C illustrate the metering sub-system during a valve statechange after a discharge stroke. As shown in FIG. 25A, after couplingpin 1310 reaching the distal end of helical groove 1342, torquecontinues to be transmitted from the output gear 1326, to the pumppiston 1306, and to the sleeve 1308 via the coupling pin 1310. Thesleeve 1308 and pump piston 1306 rotate as a unit with no relative axialmotion. The side hole 1358 (not shown in FIGS. 25A-25C) on the sleeve1308 moves between the reservoir port 1354 and the cannula port 1356.Tab 1360 moves in the direction shown by the arrow within the window1364 of manifold 1312. As shown in FIG. 25B, sleeve limit switch 1318 isclosed by the cam surface of plug 1316.

FIGS. 26A and 26B show the metering sub-system in a discharge rotationalstop position. The side hole 1358 (not shown in FIG. 26A or 26B) of thesleeve is aligned with the reservoir port 1354, the pump volume 1352 iscollapsed, and the cannula port 1356 is blocked. Plug 1316 in a stopposition, and sleeve limit switch 1318 is open. Output gear cam 1366contacts rotational limit switch 1320 to signal the end of the rotation,such that output gear 1326 stops to reverse direction.

FIGS. 27A and 27B show the metering sub-system during an intake stroke.The output gear 1326 turns the pump piston 1306 in the direction shownby the arrow in FIG. 27B. The piston 1306 is translated axially relativeto the sleeve 1308 due to interaction of the coupling pin 1310 withinthe helical groove 1364. The pump piston 1306 translates toward thegearbox, pulling fluid from the reservoir into the pump chamber 1352.During the intake stroke, friction between the seals and the outsidediameter of the sleeve 1308 should be high enough to ensure that thesleeve 1308 does not rotate relative to the manifold 1312.

FIGS. 28A to 28C show the metering sub-system during a valve statechange after an intake stroke. Coupling pin 1310 reaches the upper endof helical groove 1342, motor 1302 continues to deliver torque, causingthe sleeve 1308 and piston 1306 to rotate together. Tab 1360 on sleeve1308 moves in the direction shown in the arrow in FIG. 28A within thewindow 1364 in manifold 1312. Cam surface 1368 of plug 1316 closessleeve limit switch 1318 as plug 1316 rotates together with sleeve 1308.The sleeve 1308 and pump piston 1306 rotate as a unit with no relativeaxial motion. During this rotation the side hole 1358 of the sleeve 1308moves between the reservoir port 1354 and the cannula port 1356.

FIGS. 29A and 29B show the metering sub-system in an intake rotationalstop position. In this position, the side hole 1358 of sleeve 1308 isaligned with the cannula port 1356, the pump volume 1352 is expanded,and the reservoir port 1354 is blocked. Cam 1366 of output gear 1326engages rotational limit switch 1320 to signal that rotation iscomplete. Motor 1302 stops to reverse direction. Sleeve limit switch1318 is open.

FIGS. 30A-30C show the metering sub-system after a pump cycle iscomplete. The output gear cam 1366 is jogged off of the rotationalswitch 1320 and ready to start another cycle.

FIGS. 31A-31C illustrate another metering system 3100 a according to anexemplary embodiment of the present invention. FIG. 31A shows the motorand gearbox assembly 3101 as well as a modified pump assembly 3100. Themotor and gearbox assembly 3101 is substantially similar to the motorand gearbox assembly illustrated and described above in connection withFIGS. 13-30C.

FIG. 32 is an exploded view of the pump assembly 3100. The pump assembly3100 includes a pump manifold 3102, a port seal 3104, a seal retainer3106, a piston 3108 which rotates ±196° and translates axially ±0.038″,a coupling pin 3110, a sleeve 3112 with conductive pads, and a sleeverotational limit switch 3114 having flexure arms 3128. The sleeve 3112with conductive pads rotates ±56° as illustrated.

The pump assembly 3100 includes three flexure arms 3128 that operate asa rotational travel limit switch 3114. The rotational travel limitswitch 3114 will be described in further detail below. The rotationaltravel limit switch 3114 senses the position of the sleeve 3112directly, rather than sensing the position of the output gear. Thisallows for more precise angular alignment of the sleeve 3112 withrespect to the manifold 3102 and cannula port.

FIGS. 33A-33B illustrates the assembly of the piston 3108 into thesleeve 3112. In this embodiment an internal wall 3113 in the sleeve 3112forms the end face of the pump chamber. Features on the piston sleeveare designed with tolerances to minimize the gap between the end face ofthe piston 3108 and the face of the internal wall 3113 of the sleeve.

FIGS. 34A-34E illustrates the assembly of sleeve 3108 into the manifold3102. As illustrated the port seal 3104, the seal retainer 3106, and thesleeve 3112 are inserted into the manifold 3102. A small side hole 3115(See FIG. 34E) on the sleeve 3112 rotationally shuttles back and forthbetween a reservoir port and a cannula port, which are preferably 56degrees apart. The sleeve 3112 is inserted past a retention tab 3116(See FIG. 34D) in the manifold 3102 and is then rotated into position toprevent axial travel. Because this embodiment prevents or minimizesaxial movement of the plug, occlusion sensing by axial movement of theplug is typically not provided.

FIG. 35 illustrates a cross section of the sleeve 3112 and manifold 3102assembly taken through the port seal 3104 and through the axes of sideports to the manifold 3102. The side ports to the manifold 3102 includethe cannula port 3118 and reservoir port 3120. The port seal 3104 is aface seal, which is compressed between the sleeve 3112 outer diameterand a recessed pocket in the manifold 3102.

FIGS. 36A-36C are cross sections through the axes of the side ports asthe sleeve 3112 rotates from the reservoir port 3120 to the cannula port3118, to illustrate the valve state change. In the initial positionshown in FIG. 36A, the sleeve side hole 3115 is open to the reservoirport 3120. In this position the cannula port 3118 is blocked. In theintermediate position shown in FIG. 36B, the sleeve side hole 3115 isblocked by the port seal 3104 during the transition. In the finalposition shown in FIG. 36C, the sleeve side hole 3115 is open to thecannula port 3118. In this position the reservoir port 3120 is blocked.

FIGS. 37 a -37D illustrates the operation for the sleeve rotationallimit switch 3114. A three contact switch design allows the patch systemto distinguish between the two rotational limits via switch inputsignals rather than through tracking the sleeve's angular orientationvia software. Manifold 3102 preferably includes manifold mounting posts3122. The switch contacts 3114 are bonded to the posts 3122 withadhesive, ultrasonic welding, heat stake, or any other suitable bondingmethod. Sleeve 3112 includes conductive pads 3124 on the end of sleeve3112. These may be printed or over-molded metal inserts, or may beprovided by any other suitable means. Sleeve rotational limit switch3114 includes a plastic over-mold 3126 for spacing and mounting featuresfor the flexures. Sleeve rotational limit switch 3114 also includesthree metal flexures 3128. Manifold 3102 is provided with alignmentslots 3130, which receive the flexures 3128. In a first position, shownin FIG. 37B, the side hole 3115 on the sleeve 3112 is aligned to thecannula port 3118. In this position, a conductive pad 3124 on the sleeve3112 bridges the center and right contacts 3128 a, 3128 b. In the middleposition, shown in FIG. 37C, the side hole 3115 on sleeve 3112 is midwaybetween ports 3118 and 3120. In this position, both sides of the switch3114 are open. In the final position, shown in FIG. 37D, the side hole3115 on sleeve 3112 is aligned to reservoir port 3120. In this position,conductive pad 3124 on the sleeve 3112 bridges the center and leftcontacts, 3128 b, 3128 c.

The pump described above has a modified operating sequence. Theoperating sequence is substantially the same as that described above,with the exception that the 20° back jog is no longer required. The backjog is not required with the three contact switch design described aboveand a complete pump cycle consists of the following four segments.First, there is an approximately 140° pump discharge, which iscounterclockwise when viewing from the pump toward the gearbox. Second,there is a 56° valve state change, which is also counterclockwise.Third, there is an 140° pump intake, which is clockwise. Fourth, thereis a 56° valve state change clockwise. The total pump cycle requires 196degrees of output gear rotation in each direction.

FIGS. 38A and 38B illustrate an exploded view of another version of thepump assembly with elastomeric port and piston seals over-molded ontothe manifold and pump piston respectively. This version of the pumpfunctions in a manner substantially identical to the one describedabove, but has fewer discrete components and is easier to assemble.Over-molding seals directly onto the manifold and piston reduces thenumber of dimensions contributing to seal compression, allowing fortighter control and less variability in seal performance.

FIG. 39A illustrates an exploded view of a pump assembly 3900 with analternative rotational limit switch design. This version of the pumpassembly includes a two contact design for the sleeve rotational limitswitch. With this design, the pump would properly jog backwards at theend of a pump cycle so that the contact switch 3902 would be open in therest state. As illustrated in FIG. 39B, in a first position the sidehole 3115 on the sleeve is aligned to the cannula port. In thisposition, a first rib 3904 on sleeve forces the contracts closed. In amid-position shown in FIG. 39C, the side hole 3115 on sleeve is midwaybetween ports, and neither rib 3904, 3906 touches the contact switch3902 so it is open. In a third position shown in FIG. 39D, the side hole3115 on the sleeve is aligned to the reservoir port. In this position, asecond rib 3906 on sleeve again forces the contact switch 3902 closed.

FIG. 40 is an exploded view of another exemplary embodiment of ametering assembly 4000. This embodiment shares substantial similaritieswith the embodiments described above so the following descriptionfocuses on the differences. Metering assembly 4000 includes a sleeve4002 having a helical groove 4004, a plug 4006, seals 4008, plunger4010, coupling pin 4012, manifold 4014, port seal 4016, and flexibleinterlock 4018. FIG. 41 illustrates the metering assembly in assembledform. Seals 4008 are preferably formed of an elastomeric material, andare unitary in construction. One seal 4008 is mounted onto plug 4006,and the other seal 4008 is mounted onto plunger 4010. Plug 4006 ispreferably fixed into sleeve 4002 by gluing, heat sealing, or any othersuitable means. An end face of the plug forms one surface of the pumpvolume. Plunger 4010 is inserted into sleeve 4002, and coupling pin 4012is press fit into the plunger 4010 and extends into helical groove 4004to provide axial translation of the plunger 4010 as it is rotated by themotor (not shown). An end face of the plunger 4010 forms an opposingsurface of the pump volume. Port seal 4016 is preferably a single moldedpiece of elastomeric material. This embodiment reduced the number ofparts, and improves manufacturability. FIG. 42 is a cross section of theassembled metering assembly.

FIGS. 43A-43C illustrate the interaction of the interlock 4018 with thesleeve 4002. As shown in FIG. 41 , interlock 4018 is mounted ontomanifold 4014 at either end of interlock 4018. As shown in FIG. 43A, anend face of sleeve 4002 includes a detent 4020 that is adjacent to abump 4022 of the interlock 4018 when the metering assembly is in a firstposition (side hole aligned with reservoir pump). Under certainconditions, such as back pressure, it is possible that friction betweenthe piston 4010 and the sleeve 4008 is sufficient to cause the sleeve torotate before the plunger 4010 and coupling pin 4012 reach either end ofthe helical groove 4004. This could result in an incomplete volume ofliquid being pumped per stroke. In order to prevent this situation,interlock 4018 prevents sleeve 4002 from rotating until the torquepasses a predetermined threshold. This ensures that piston 4010 fullyrotates within sleeve 4008 until the coupling pin 4012 reaches the endof the helical groove 4004. Once the coupling pin hits the end of thehelical groove 4004, further movement by the motor increases torque onthe sleeve beyond the threshold, causing the interlock to flex andpermit the detent 4020 to pass by the bump 4022. This is illustrated inFIG. 43B. At the completion of rotation of the sleeve 4008 such that theside hole is oriented with the cannula port, the detent 4020 moves pastthe bump 4022 in interlock 4018. This is illustrated in FIG. 43C.

FIG. 44 illustrates a cross section of another exemplary embodiment of ametering system 4400. The metering system 4400 includes a modifiedsleeve 4402 that has a face 4404 forming one surface of the pump volume.This embodiment eliminates the need for a plug as in the previousembodiment, and simplifies manufacturing.

FIG. 45 illustrates another exemplary embodiment having a modifiedsleeve 4500 and switching mechanism 4502. FIG. 46 is a perspective viewof the modified sleeve 4500, which includes a detent 4504 similar to thesleeve described above to interact with an interlock (not shown). Switchmechanism 4502 includes a limit switch arm 4506 adapted to rotate ineither direction away from its neutral position. Sleeve 4500 includes aswitching lever (actuator arm) 4508 adapted to interact with the limitswitch 4506 as the sleeve 4500 rotates. FIG. 47 illustrates how limitswitch 4506 rotates about an axis. Switch mechanism 4502 provideselectrical signals to indicate the position of limit switch 4506. FIG.48 is a top view illustrating sleeve 4500 rotated to an orientationwhere limit switch 4506 has rotated to its maximum angle (alpha) fromthe neutral position. Further rotation of the sleeve causes the limitswitch 4506 to be free of actuator arm 4508 and to return to its neutralposition. This change in orientation of the switch arm indicates the endof the rotation of sleeve 4500 in one direction, and causes therotational metering pump to reverse. FIG. 49 is a side elevation vieworiented towards the sleeve face, illustrating the same interactionbetween limit switch 4506 and actuator arm 4508. FIG. 50 is a sideelevation view, showing sleeve 4500 and switching mechanism 4502incorporated into a patch pump, together with interlock collar 4510.

FIG. 51A illustrates the relative angular positions of the limit switch4506 and actuator arm 4508. Alpha a is the angle of the limit switch4506. Beta β is the angle of the rotating sleeve and actuating arm. FIG.51B illustrate the relative change d(α)/d(β) vs. ρ. Reversal ispreferably triggered at β=33°. As illustrated, as actuating arm 4608rotates, it pushes limit switch 4506 away from the neutral position(α=0°). When actuating arm angle β reaches approximately 30β theactuating arm 4508 clears the limit switch 4506, and limit switch 4506returns to neutral (α=0°), thereby initiating a reversal of therotational pump. The same procedure occurs in reverse as the sleeve 4508rotates in the other direction. Accordingly, the sleeve reciprocatesback and forth.

Improved plunger and pump plug parts will now be described in connectionwith FIGS. 52-67 . As will now be described the improved plunger 5210and pump bottom 5206 improve the pump by making these parts easier tomanufacture and assemble, and by eliminating a potential source of fluidleak from the prior design. Plunger 5210 is illustrated in multipleviews in FIGS. 52-58 . Plunger 5210 is substantially similar to theplunger 4010 illustrated in FIG. 40 , except that O-ring 4008 is notneeded, because a seal, to be described below, is overmolded onto thehead 5212 of the plunger 5210.

Seal 5214 is illustrated in multiple views in FIGS. 59-62 . Seal 5214 isadvantageously overmolded onto the head 5212 of plunger 5210.Accordingly, the plunger with seal is advantageously manufactured in atwo-shot molding process. Plunger 5210 is molded of a rigid plasticmaterial, and then the seal 5214 is molded out of a viscoelasticelastomer onto the plunger 5210 as a second shot. The combined plunger5210 and seal 5214 is more easily assembled into the overall pump, andreduces the chances for leakage present with an O-ring design.

A pump stopper or plug 5206 is illustrated in FIGS. 63-67 . The stopper5206 substantially corresponds to the plug 4006 in FIG. 40 , except thata seal 5214 (the same or substantially similar seal part may be used forboth the plunger 5210 and stopper 5206) is overmolded onto the head 5208of stopper 5206 in place of an O-ring. Similar to the plunger 5210described above, stopper 5206 and seal 5214 are preferably manufacturedin a two-shot molding process. Stopper 5206 is molded from rigid plasticmaterial, and seal 5214 is molded out of a viscoelastic elastomer ontothe stopper 5206 as a second shot.

FIG. 68 illustrates an exploded view of metering assembly 4000, but withthe improved plunger 5210, stopper 5206, and seals 5214. It will beappreciated by those of ordinary skill in the art that just as the plug4006 was optional in the prior design and could be replaced with a wall4404 as illustrated in FIG. 44 , so the stopper 5206 is optional andreplaceable with a similar wall.

A method 6900 of manufacturing and assembling a pump according to anexemplary embodiment of the invention utilizing the overmolded partsdescribed above will now be described in connection with FIG. 69 .First, a plunger is molded from rigid plastic at step 6902. Next, a sealis overmolded onto a head of the plunger at step 6904. The seal ismolded from a viscoelastic elastomer, and is dimensioned to fit withinand seal a pump chamber. Optionally, a pump stopper is molded from rigidplastic at step 6906, and a seal is overmolded onto the head of the pumpstopper at step 6908. The plunger and pump stopper are inserted into apump chamber of a pump at step 6910. A pin is inserted into a hole inthe plunger to enable translating of the plunger axially as the pumpmotor rotates the pump chamber at step 6912.

Although only a few illustrative embodiments of the present inventionhave been described in detail above, those skilled in the art willreadily appreciate that many modifications are possible in theillustrative embodiments, and various combinations of the illustrativeembodiments are possible, without materially departing from the novelteachings and advantages of this invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention.

What is claimed is:
 1. A method of manufacturing a rotational meteringpump, comprising, molding a plunger from rigid material; overmolding aseal onto a head of the plunger, the seal comprising viscoelasticelastomer; inserting the plunger and seal into a pump chamber; andinserting a pin into a hole in the plunger through a helical slot in asleeve comprising the pump chamber; the sleeve comprising a tab toprevent axial movement of the sleeve relative to a manifold.
 2. Themethod of claim 1, further comprising molding a pump stopper from rigidmaterial; overmolding a second seal onto a head of the pump stopper, thesecond seal comprising viscoelastic elastomer; and inserting the pumpstopper into the pump chamber.